But anyone venturing inside encounters a sinister scene: a stuffy boxroom in which thousands of dogs have allegedly met their deaths.

“It stinks of dead dogs in there,” said Jane, a former staff member who worked at the site in Greater Manchester for years.

“It is a sickening smell.”

The dominant features of the white-walled and red-floored room are two industrial-sized freezers.

They are the last stop on what former staff and greyhound trainers say is a conveyor belt of killing, starting with dogs being delivered at the sanctuary’s front desk on an almost daily basis; leading to lethal drugs fired directly into their chests; and ending with the bodies dumped in the freezers.

Ostensibly the sanctuary, which has been open since 1975 to rehome unwanted animals, is offering succour to dogs found wandering the streets by council dog wardens or brought in by owners who no longer feel able to look after their pets.

But the reality behind the facade is that, according to the testimony of former staff members, about half of all the dogs entering will be killed, often within days or even hours.